Storage library systems are often used by enterprises and the like to efficiently store and retrieve data from storage media. In the case of some storage libraries, the media are data cartridges (e.g., tape cartridges) that are typically stored and indexed within a set of magazines. When particular data is requested, a specialized robotic mechanism finds the appropriate cartridge, removes the cartridge from its magazine, and carries the cartridge to a drive that is designed to receive the cartridge and read its contents. Some storage libraries have multiple drives that can operate concurrently to perform input/output (IO) operations on multiple cartridges.
To operate properly, the robotic mechanisms are expected to reliably (e.g., repeatably and accurately) and rapidly find, retrieve, and deliver desired cartridges throughout the storage library cartridge inventory. This functionality can be facilitated by configuring the robotic mechanism to move a hand assembly in at least three axes (e.g., x, y, and z directions, and sometimes one or more of pitch, roll, or yaw), and to include one or more sensors to reliably detect the position and/or orientation of the hand assembly. When in its desired location, the hand assembly is activated to reliably grip the desired cartridge and remove it from a magazine or drive, or to reliably release the cartridge into a desired magazine slot or drive.
In many implementations, it is desirable for the robotic library to have free running mechanisms to glide smoothly between locations. However, it may be necessary to securely station the robotic mechanism in its desired location to repeatably and reliably perform certain types of operations, such as pick and place operations. Accordingly, implementations of robotic mechanisms may include complex designs to facilitate the two-state operation where the robotic mechanism can move in a substantially frictionless manor and park in a substantially locked manner.